Abstract Quasi free standing monolayer graphene (QFMLG), grown on SiC by Si evaporation from the Si-rich SiC(0001) face and H intercalation, displays irregularities in STM and AFM images appearing as localized features, associated with vacancies in the H layer coverage. Size, shape, concentration, and distribution of these features depend on hydrogenation conditions. In order to understand this phenomenology and possibly control it, we perform a Density Functional Theory study of QFMLG with defects in the H coverage of different size and shape and arranged in different configurations. We show that H vacancies generate localized states with highly specific electronic structure. Based on the comparison of simulated and measured STM images we are able to associate different vacancies of large size (7-13 missing H) to the observed features, unraveling the structural diversity of defects of H coverage in QFMLG. Our study indicates a tendency of single H vacancies to aggregate and to locate on a regular superlattice, providing insight into the kinetics of the hydrogenation process. The energy of the localized states associated with these vacancies depends on their size and shape, showing dependence of the electronic properties on the environmental conditions during the sample production.

中文翻译：

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通过密度泛函理论解开准独立单层石墨烯中的局域态

摘要 准独立式单层石墨烯 (QFMLG)，通过从富硅 SiC(0001) 面蒸发和 H 嵌入在 SiC 上生长，在 STM 和 AFM 图像中显示不规则性，表现为局部特征，与 H 层覆盖中的空位相关. 这些特征的大小、形状、浓度和分布取决于氢化条件。为了理解这种现象并可能对其进行控制，我们对 QFMLG 进行了密度泛函理论研究，其中 H 覆盖层中存在不同大小和形状并以不同配置排列的缺陷。我们表明 H 空位产生具有高度特定电子结构的局部状态。基于模拟和测量 STM 图像的比较，我们能够将不同的大尺寸空位（7-13 个缺失的 H）与观察到的特征相关联，揭示 QFMLG 中 H 覆盖缺陷的结构多样性。我们的研究表明，单个 H 空位倾向于聚集并位于规则的超晶格上，从而深入了解氢化过程的动力学。与这些空位相关的局域态的能量取决于它们的大小和形状，显示出样品生产过程中电子特性对环境条件的依赖性。